SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50fc6b5cad046cdff5458285ebb7050083c660fd01cc5b2490e2e8160992cdd3' 
  AND token = 'Q7b3de6DhnD7NR13uzUKD9sQ5Gl7gTJHGjU/hAC7k4s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}